Preparation of cotton yarns from slivers and rovings

ABSTRACT

Cotton fibres or rovings or slivers are subjected to the action of a swelling agent without tension being exerted on them. The swelling agent should be capable of transforming the material into cellulose II. The fibres shrink while still in the presence of the swelling agent and subsequently the fibres are restretched to 95 - 110% of their original length before swelling. Then while maintaining these dimensions the fibres or rovings or slivers are rinsed or neutralised and rinsed and while still maintaining these dimensions they are dried at temperatures exceeding 70*C. The fibres or slivers or rovings can be given a resin finish and they will not show the usual degradation of properties.

United States Patent De Boer et a1.

[ PREPARATION OF COTTON YARNS FROM SLIVERS AND ROVINGS 175] Inventors: Jan J. De Boer, Pijnacker; Herman Borsten, Voorschoten, both of Netherlands 22 Filed: Nv. 21,1973

[21] Appl. No.: 418,048

Related US. Application Data [62] Division of Ser. No, 221,762, Jan. 28, 1972, Pat. No.

[] Foreign Application Priority Data Feb. 19, 1971 United Kingdom 4982/71 [52] US. Cl 28/76 R; 8/125; 57/164 [51] Int. Cl D06m 1/10 [58] Field of Search 57/35, 164, 157 R, 157 TS, 57/157, 156; 28/74 R, R, 76 R; 8/125,

195, DIG. 3

[56] References Cited UNITED STATES PATENTS 1,901,095 3/1933 Goldthwait 8/125 June 17, 1975 2,205,120 6/1940 Heberlein, Jr. et al. 8/125 X 2,449,215 9/1948 Goldthwait et al. 57/164 3,285,690 11/1966 Cooper et al. 57/164 X 3,403,504 10/1968 Hamplainen et a1 57/164 3,498,739 3/1970 Murphy et al. 8/125 Primary Examiner-John Petrakes Attorney, Agent, or Firm--Brumbaugh, Graves, Donohue & Raymond [57] ABSTRACT Cotton fibres or rovings or slivers are subjected to the action of a swelling agent without tension being exerted on them. The swelling agent should be capable of transforming the material into cellulose 11. The fibres shrink while still in the presence of the swelling agent and subsequently the fibres are restretched to of their original length before swelling. Then while maintaining these dimensions the fibres or rovings or slivers are rinsed or neutralised and rinsed and while still maintaining these dimensions they are dried at temperatures exceeding 70C. The fibres or slivers or rovings can be given a resin finish and they will not show the usual degradation of properties.

8 Claims, No Drawings 1 PREPARATION OF COTTON YARNS FROM SLIVERS AND ROVINGS This is a continuation, division, of application Ser. No. 221,762, filed Jan. 28, 1972, now US. Pat. No. 3,822,994.

FIELD AND BACKGROUND OF INVENTION The invention concerns a method of preparing cotton fibres, slivers, or rovings which is based upon the application of definite swelling, stretching, rinsing, and drying treatments on fibres, slivers and rovings. The fibres obtained have a distinctly higher strength and an improved response to subsequent easy-care finishing.

In extreme circumstances the increase in fibre strength may amount to about 200% of the original strength.

If the treatment of the fibres is followed by a reactant application using the usual methods, then at most only a small decrease of strength will be observed.

This fact is in contrast with the behaviour of un treated cotton which shows a strength decrease of 30 50% after the same reactant treatment.

The invention comprises the steps of swelling the cotton fibres or slivers or rovings without tension in a swelling agent so as to obtain cellulose II as e.g.: caustic soda with a concentration of at least 12% NaOH, or preferably higher, e.g., 24% NaOH. Next the swollen, and thus strongly shrunk, material is stretched to a level of 95 1 15% of its original length in the caustic soda and further, if necessary, during rinsing.

Finally the material is dried while maintaining the dimensions reached. The fibres or slivers or rovings obtained in this way are spun either in the wet or the dry state into weaving or knitting yarns.

Treating yarns by using the technique described is not recommended, because an essential change in the yarn structure involving a very low elongation of the yarn will occur. A reactant finishing process using the treated fibrous materials does not lead, or does so only to a small extent, to a decrease of the strength proper ties of the fibres and yarns respectively of the fabrics prepared from these fibres and yarns.

Concerning the procedures used, the following remarks can be made.

To prevent slipping from occurring during the stretching treatments it is desirable to twist the slivers and rovings to such a degree that during stretching in the swelling phase destruction of the yarn structure cannot occur, which means that the load applied is transferred to the fibres. On the other hand, it is not desirable to choose the degree of twist higher than is strictly necessary to prevent insufficient penetration of the material during the swelling phase. The shinkage occurring during swelling may be about 15 The restretching of the fibres or slivers or the rovings may be carried out by a conventional method, e.g., by stretching between two pairs of rollers, the second pair of which has a higher speed than the first pair. In some cases use can be made of two clamps holding the yarn by enlarging the distance between them. The restretching treatment should preferably start when the material is still completely swollen, as only then are the necessary high stretching levels easily obtained using relatively low loads at that time.

It is desirable to maintain the final stretching level in the caustic soda and during rinsing for at least 1 4 minutes.

If the caustic soda is removed completely before restretching it is very often impossible, even by applying large loads, to realize the desired degree of restretching. In general, material breakage will occur. The caustic soda should preferably be removed completely before the final drying treatment.

If a complete caustic removal cannot be reached before drying, the rinsing treatment may be repeated after drying.

Especially if the material is wet spun, twistless, followed by wet uptwisting so as to obtain a yarn, this method is less disturbing. If a dry spinning method is applied a complete removal of the caustic soda preceding drying is necessary.

It may be remarked, however, that traces of caustic soda and salts remaining in the dry fibrous material may have very unfavourable effects on the mechanical properties of the fibrous material.

During dry spinning it may be necessary to untwist the treated slivers o'r rovings before passing on to the final spinning treatment. It is preferable that the drying treatment should be carried out in such a way that at least the final length reached during swelling and rinsing is maintained. Experience shows that imperfections caused during swelling as a consequence, e.g.. of an imperfect penetration of the caustic soda into the material, may be nearly completely eliminated by using a high degree of restretching during the drying treatment. Thus, even fibres which are stretched insufficiently show an essential improvement of the tensile properties if restretching is applied to as high a degree as possible. Subsequently, the drying treatment contributes quite essentially to the effect which is desired. In fact, drying should lead to a setting of the structural changes introduced into the fibres by applying the treatments mentioned above. In order to obtain an almost ideal setting, the moisture should be removed as much as possible without damaging the fibre material thermally. Based upon experiments carried out, drying by means of infra-red radiation meets the abovementioned requirement.

However, it has appeared that other drying methods also lead to the results desired. On the basis of examples some aspects discussed will be illustrated. In the examples to be given use was made of different cotton varieties. It should be noted, however, that a mutual comparison of the results is not always proper.

EXAMPLE I Fibre treatments A bundle of cotton fibres was swollen without tension in 24% NaOH. After complete swelling, the fibres were restretched to between and of the original length. Restretching was carried out during swelling and rinsing of the caustic soda. Their final dimensions reached during restretching were maintained for at least one minute.

After a complete removal of the caustic soda from the fibres, they were dried at C and/or conditioned at 65% relative humidity and 20C.

Next the conditioned material was finished using a reactant having as a catalyst MgCl in the amount of 7% of the reactant weight. The reactant solution was applied in a quantity equal to the weight of the fibres. After storage for one hour at room temperature and 100% relative humidity, the fibres were dried at 70C and then baked for 5 min at C.

After washing with 1% solution of neutral soap and rinsing, the fibres were conditioned again. The values obtained for the fibre strength of one cotton variety are compiled in Table l From this data it appears that the Table 2 Blank Treated 7t Fixapret 0 4% 6 0 3 4% 6 Yarn strength (g/teX) 21.0 13.0 12.0 10.4 23.4 22.2 20.6 21.8

Elongation at break (71) 5.7 4.1 3.3 3.1 3.5 3.9 4.0 3.6

Fibre strength Elongation at break (70 6.5 4.5 3.3 3.3 5.0 4.5 4.4 4.2

Nitrogen content 0.58 0.35

described method leads to very strong fibres even after These results agree with those reached after the applying a reactant. Other cotton varieties lead to comtreatment of the separate fibres. The efficiency of the pletely analogous results (see example IV), however roving treatment is good. the actual strength increase reached may vary after the Fixapret CPN is a product manufactured by BASF in application of the reactant (example IV). West Germany for the purpose of finishing cotton TABLE 1.

Tensile strength in grams without resin finish after resin finish pre-treatment conditioned dried at 120C conditioned dried at 120C without maintained without maintained without maintained without maintained tension length tension length tension length tension length none 6.0 6.0 6.5 6.5 4.0 4.0 4.0 4 .0

mercerized without tension and without 8.5 8.5 9.0 9.0 4.5 4.5 6.5 4.0

after-stretching mercerized without tension and with an after-stretching to 9.5 10.0 10.0 10.5 7.0 8.5 10.5 10.0

10071 of the length before mercerization mercerized without tension and with an after-stretching to 11.0 11.5 10.0 11.0 7.5 10.5 9.5 10.5

10572 of the length before mercerization EXAMPLE II Roving treatment Use was made of a hypochlorite bleached 300 tex roving. The material consisted of the following industrial cotton mixture:

70% Columbia 25% Mozambique 5% Greek This roving was available in a sufficient quantity and preliminary trials gave satisfactory results.

The material was treated like the yarn (see example I).

To prevent as much breakage as possible, the twist was increased to 1 10 turns per meter. As it was difficult to remove the caustic, the material was treated with acetic acid, dried and coned. Next it was rinsed very thoroughly in a yarn apparatus. Finally, the wet material was spun twistless. In order to obtain the best normal yarn possible, the twistless material was uptwisted in the moist state. To obtain comparable material an unmercerised roving was spun in the same way and uptwisted. In this way a 27 tex yarn was made applying a twist of 700 turns per metre.

products and contains essentially dimethylolhydroxyethylurea.

EXAMPLE III Fabric prepared from treated fibres From fibres treated as described in Example I, after spinning, a plain weave fabric was woven having these specifications: warp 32 threads/cm; weft 31 threads/cm; g/m Subsequently, Fixapret CPN was applied to this fabric according to the directions of the manufacturer, thus including the usual additives.

All properties were measured on samples washed 5 times. With reference to Table 3 relating to some properties of the fabric, the following conclusions may be drawn.

The treated material shows a clearly greater strength when the reactant has been applied. Generally speaking the total elongation does not show large differences. The tearing strength of the reactant treated preswollen material is better and this tendency is more pronounced with an increasing reactant content.

5 6 The dry crease recovery angle of the'preswollenmal. A process for preparing a cotton yarn'with imterial without reactant is somewhat higher than that of proved tensile strength retaining properties comprising: the blank material. When the reactant has been applied a. selecting a material from the group consisting of the differences disappear. cotton fibres, slivers, and rovings;

The wet recovery angles are nearly the same for 5 b. soaking the unrestrained material in a swelling blank and treated material. agent to transform the material into Cellulose 11;

Table 3 Fibre, yarn and fabric Non treated Treated properties ixapret CPN (7r) 3 6 3 6 Fibre strength (g) 3.7 2.0 1.9 6.4 5.6 4.9 Elongation at break (7r) 3.6 2.7 5.4 4.2 Yarn: Strength (g/tcx) 20.0 10.9 8.2 17.8 12.1 10.9

arp Weft 18.7 9.5 7.8 17.6 12.6 12.6 Elongation at 7.3 4.0 4.1 5.5 3.3 4.2

arp break (71) Weft 6.7 5.4 5.3 4.9 3.9 4.1 Fabric: Tensile strength 61 39 34 59 52 50 arp (kg/ cm) Weft 57 40 34 62 52 42 Elongation at 18 9 6 18 10 10 arp break ('2 Weft 16 14 10 12 12 12 Tearing strength 1 140 860 650 1230 1570 1210 arp (g) Weft l 180 740 500 1330 1470 1 180 Crease recovery 57 l 14 142 67 l 1 1 135 arp angle (dry) Weft 47 110 136 61 105 127 Crease recovery 65 93 105 66 79 1 15 arp angle (wet) Weft 59 89 123 70 106 111 EXAMPLE IV c. stretching the material, in the presence of the swelling agent, to a length between 95% to l 10% of the original length of the material before the soaking step, the stretched length being continu ously maintained during the remaining steps of the process;

d. rinsing the material while in the stretched condition to remove the swelling agent;

e. drying the material while in the stretched condition Results using different cotton varieties In order to illustrate the effect of reactant finishing on different cotton varieties, the fibre strength and elongation values for different cotton varieties before and after mercerising (fibre bundle) and after applying 9% Fixapret CPN according to the usual technique (see example I) are given in Table 4.

Table 4 at a temperature in excess of 70C in order to set the improved tensile strength properties obtained; Blank material Treated material and t g i agg f. spinning the material into a yarn. s ren a ion s r g strength 2. The process of claim 1 wherein sa1d rinsing step lgg effects a complete removal of the swelling agent. (g) /1 (g) ('71) in blank 3. The process of claim 1 further comprising the step A l of neutralising any remaining swelling agent with an 80 130 5.5 10 acid following said rinsing step. Pakistan 4. The process of cla1m 3 wherein said acid is acetic dessi 8.0 l 1.0 16.0 7.0 2.0 Russian acl Pervyi 4.0. 11.0 6.5 6.5 1.6 5. The process of clalm 1 further comprising the steps ig? 3 8 0 9 0 M) of conditioning the material at a relative humidity in Peruvian excess of and at a temperature in excess of 15C 6 9 after said drying step. 532 m 60 6. The process of claim 1 wherein said drying step is Amana accomplished by lnfrared radiation. Pifigggj 35 10.0 m m 3,0 7. The process of preparing a cotton fabric with easy care qualities and increased tensile strength comprising: From this data it appears, that the treatment applied, a. selecting a material from the group consisting of led in all cases to a relatively very high fibre strength cotton fibres, slivers. and rovings; while a high elongation at break level was maintained. b. soaking the unrestrained material in a swelling We claim: I agent to transform the material into Cellulose ll;

at a temperature in excess of C in order to set the improved tensile strength properties obtained; f. spinning the material into a yarn; g. weaving or knitting a fabric from said yarn; and h. treating said fabric with a suitable resin finish, 8. The process of claim 7 wherein said resin finish essentially comprises dimethylolhydroxyethylurea.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3, 889,328

DATED I June 17, 1975 |NV,ENTOR(5) 3 Jan J. DeBoer et al.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. 1, line Col. 1, line Col. 4, line Col. 5, line raised one Col. 5, line raised one Col. 5, line raised one Col. 5, line raised one Col. 5, line raised one Col. 5, line raised one Col. 5, line raised one [SEAL] 3, delete "continuation,"; 55, before "slivers" insert the-;

Signed and Scaled this fourth D3) of November 1975 A ttes t:

RUTH C. MASON Arresting Officer Warp-- and 20.0"; Warp and "7.3"; Warp and "61"; --Warp and "18"; -Warp and "1140"; -Warpand "57"; and Warp-- and "65" .0" should read -4.0-;

should be should be should be should be should be should be should be C. MARSHALL DANN Commissioner oflarems and Trademarks 

1. A PROCESS FOR PREPARING A COTTON YARN WITH IMPROVED TENSILE STRENGTH RETAINING PROPERTIES COMPRISING: A. SELECTING A MATERIAL FROM THE GROUP CONSISTING OF COTTON FIBRES, SLIVERS, AND ROVINGS: B. SOAKING THE UNRESTRAINED MATERIAL IN A SWELLING AGENT TO TRANSFORM THE MATERIAL INTO CELLULOSE II; C. STRETCHING THE MATERIAL, IN THE PRESENCE OF THE SWELLING AGENT, TO A LENGTH BETWEEN 95% TO 110% OF THE ORIGINAL LENGTH OF THE MATERIAL BEFORE THE SOAKING STEP, THE STRETCHED LENGTH BEING CONTINOUSLY MAINTAINED DURING THE REMAINING STEPS OF THE PROCESS; D. RINSING THE MATERIAL WHILE IN THE STRETCHED CONDITION TO REMOVE THE SWELLING AGENT; E. DRYING THE MATERIAL WHILE IN THE STRETCHED CONDITION AT A TEMPERATURE IN EXCESS OF 70*C IN ORDER TO SET THE IMPROVED TENSILE STRENGTH PROPERTIES OBTAINED; AND F. SPINNING THE MATERIAL INTO A YARN.
 2. The process of claim 1 wherein said rinsing step effects a complete removal of the swelling agent.
 3. The process of claim 1 further comprising the step of neutralising any remaining swelling agent with an acid following said rinsing step.
 4. The process of claim 3 wherein said acid is acetic acid.
 5. The process of claim 1 further comprising the steps of conditioning the material at a relative humidity in excess of 60% and at a temperature in excess of 15C after said drying step.
 6. The process of claim 1 wherein said drying step is accomplished by infrared radiation.
 7. The process of preparing a cotton fabric with easy care qualities and increased tensile strength comprising: a. selecting a material from the group consisting of cotton fibres, slivers, and rovings; b. soaking the unrestrained material in a swelling agent to transform the material into Cellulose II; c. stretching the material, in the presence of the swelling agent, to a length between 95% to 110% of the original length of the material before the soaking step, the stretched length being continuously maintained during the remaining steps of the process; d. rinsing the material while in the stretched condition to remove the swelling agent; e. drying the material while in the stretched condition at a temperature in excess of 70*C in order to set the improved tensile strength properties obtained; f. spinning the material into a yarn; g. weaving or knitting a fabric from said yarn; and h. treating said fabric with a suitable resin finish.
 8. The process of claim 7 wherein said resin finish essentially comprises dimethylolhydroxyethylurea. 